1. Field of the Invention
The present invention relates to an automatic vehicle transmission having a planetary gear train connected to an input shaft, which planetary gear train is connected to an output shaft through a CVT variable speed drive having two drive shafts and at least one gear pairing. The transmission includes at least three clutches, the operation of which enables selection of the gear ranges R, N, D-Low, and D-High.
2. Description of the Related Art
A vehicle transmission of the type described above is known from International Patent Publication No. WO 2004/038257. In that arrangement the input shaft of the transmission, which is connected to an internal combustion engine through a torque converter, is connected to the planet carrier of the planetary gear train. The ring gear of the planetary gear train is connected to the drive shaft of the variable speed drive on which an output shaft gear is supported that is non-rotatably connected to an output shaft. The output shaft gear is connected through a clutch to the one variable speed drive shaft in a rotationally fixed connection. The sun gear of the planetary gear train meshes with a first intermediate shaft gear that is non-rotatably connected to an intermediate shaft on which a second intermediate shaft gear is supported and which meshes with the output shaft gear and is non-rotatably connected by means of a clutch to the intermediate shaft. The first intermediate shaft gear also meshes with a gear that is non-rotatably connected to the other variable speed drive shaft on which another gear is rotatably supported and which is non-rotatably connected to the other variable speed drive shaft through a reverse travel clutch.
An object of the present invention is to provide an automatic vehicle transmission of the type described above that operates at good efficiency, that enables widely spread forward gear ranges, and that enables the installation of a torque converter in such a way that the resulting increase in torque does not go through the variable speed drive when conversion occurs.